1. Field of the Invention
The present invention relates to an image processing apparatus which corrects gradation and color reproduction characteristics of an image photographed (or shot) by a digital camera or the like, an image processing method which is applied to the image processing apparatus, a recording medium which stores a program to execute the image processing method, and the program itself.
2. Related Background Art
Conventionally, in a case where an image photographed (or shot) by a digital camera is input into, e.g., a PC (personal computer) and the input image is displayed on a display such as a CRT (cathode ray tube) or printed by a printer such as an inkjet printer as it is, there are some cases where an image of optimum characteristics (e.g., lightness, color reproducibility, etc.) cannot be output. In these cases, the image characteristics are improved by controlling an exposure process and improving a color process in the digital camera. For example, when a person is photographed against light, a face portion of the subject (i.e., the person in question) might become dark, and/or the color of the face of the person in question might become yellowish due to adjustment of entire white balance. Particularly, it is desired to improve these characteristics in regard to a person image. Moreover, it is desired to reproduce a characteristic that human beings feel desirable, in regard to gradation reproducibility and color reproducibility in a person's skin region.
Incidentally, as methods of performing image data correction to obtain desirable color reproducibility in regard to a specific subject, the following technical methods are disclosed. That is, Japanese Patent Application Laid-Open No. 2001-092956 discloses a first proposal for the method of converting each representative color into a color characteristic that human beings feel desirable. Besides, Japanese Patent Application Laid-Open No. 2001-238177 discloses a second proposal for the method of extracting a face region in image data photographed in a person mode and processing the extracted region so that a flesh color finishes beautifully.
However, in the above first proposal, it is necessary to designate a specific target region in the image so as to determine the representative value, whereby there is a problem that an operation is complicated. Besides, in the above second proposal, there is a problem that the image including the face region is complicatedly composed of an image that a process effect can be expected, an image that a process effect cannot be expected, and further an image that brings about a reverse effect (hereinafter called a side effect). Therefore, in regard to the image processing apparatus which displays and prints the person image photographed by the digital camera, a demand for a function to automatically correct the image data and thus output the person image of an optimum characteristic increases.